fix: add consistent collection name validation to all MCP tool methods

src/main/java/org/apache/solr/mcp/server/collection/CollectionService.java

@@ -411,6 +411,10 @@ public List<String> listCollections() {
 	public SolrMetrics getCollectionStats(
 			@McpToolParam(description = "Solr collection to get stats/metrics for") String collection)
 			throws SolrServerException, IOException {
+		if (collection == null || collection.isBlank()) {
+			throw new IllegalArgumentException(BLANK_COLLECTION_NAME_ERROR);
+		}
+
 		// Extract actual collection name from shard name if needed
 		String actualCollection = extractCollectionName(collection);
 
@@ -957,6 +961,10 @@ private boolean validateCollectionExists(String collection) {
 	 */
 	@McpTool(name = "check-health", description = "Check health of a Solr collection")
 	public SolrHealthStatus checkHealth(@McpToolParam(description = "Solr collection") String collection) {
+		if (collection == null || collection.isBlank()) {
+			throw new IllegalArgumentException(BLANK_COLLECTION_NAME_ERROR);
+		}
+
 		String actualCollection = extractCollectionName(collection);
 		try {
 			// Ping Solr

src/main/java/org/apache/solr/mcp/server/indexing/IndexingService.java

@@ -196,6 +196,10 @@ public IndexingService(SolrClient solrClient, IndexingDocumentCreator indexingDo
 	public void indexJsonDocuments(@McpToolParam(description = "Solr collection to index into") String collection,
 			@McpToolParam(description = "JSON string containing documents to index") String json)
 			throws IOException, SolrServerException {
+		if (collection == null || collection.isBlank()) {
+			throw new IllegalArgumentException("Collection name must not be blank");
+		}
+
 		List<SolrInputDocument> schemalessDoc = indexingDocumentCreator.createSchemalessDocumentsFromJson(json);
 		indexDocuments(collection, schemalessDoc);
 	}
@@ -262,6 +266,10 @@ public void indexJsonDocuments(@McpToolParam(description = "Solr collection to i
 	public void indexCsvDocuments(@McpToolParam(description = "Solr collection to index into") String collection,
 			@McpToolParam(description = "CSV string containing documents to index") String csv)
 			throws IOException, SolrServerException {
+		if (collection == null || collection.isBlank()) {
+			throw new IllegalArgumentException("Collection name must not be blank");
+		}
+
 		List<SolrInputDocument> schemalessDoc = indexingDocumentCreator.createSchemalessDocumentsFromCsv(csv);
 		indexDocuments(collection, schemalessDoc);
 	}
@@ -352,6 +360,10 @@ public void indexCsvDocuments(@McpToolParam(description = "Solr collection to in
 	public void indexXmlDocuments(@McpToolParam(description = "Solr collection to index into") String collection,
 			@McpToolParam(description = "XML string containing documents to index") String xml)
 			throws ParserConfigurationException, SAXException, IOException, SolrServerException {
+		if (collection == null || collection.isBlank()) {
+			throw new IllegalArgumentException("Collection name must not be blank");
+		}
+
 		List<SolrInputDocument> schemalessDoc = indexingDocumentCreator.createSchemalessDocumentsFromXml(xml);
 		indexDocuments(collection, schemalessDoc);
 	}

src/main/java/org/apache/solr/mcp/server/metadata/SchemaService.java

@@ -163,6 +163,10 @@ public SchemaService(SolrClient solrClient, ObjectMapper objectMapper) {
 	 */
 	@McpResource(uri = "solr://{collection}/schema", name = "solr-collection-schema", description = "Schema definition for a Solr collection including fields, field types, and copy fields", mimeType = "application/json")
 	public String getSchemaResource(String collection) {
+		if (collection == null || collection.isBlank()) {
+			throw new IllegalArgumentException("Collection name must not be blank");
+		}
+
 		try {
 			return toJson(objectMapper, getSchema(collection));
 		} catch (Exception e) {
@@ -251,6 +255,10 @@ public String getSchemaResource(String collection) {
 	 */
 	@McpTool(name = "get-schema", description = "Get schema for a Solr collection")
 	public SchemaRepresentation getSchema(String collection) throws Exception {
+		if (collection == null || collection.isBlank()) {
+			throw new IllegalArgumentException("Collection name must not be blank");
+		}
+
 		SchemaRequest schemaRequest = new SchemaRequest();
 		return schemaRequest.process(solrClient, collection).getSchemaRepresentation();
 	}

src/main/java/org/apache/solr/mcp/server/search/SearchService.java

@@ -250,6 +250,10 @@ public SearchResponse search(@McpToolParam(description = "Solr collection to que
 			@McpToolParam(description = "Number of rows to return", required = false) Integer rows)
 			throws SolrServerException, IOException {
 
+		if (collection == null || collection.isBlank()) {
+			throw new IllegalArgumentException("Collection name must not be blank");
+		}
+
 		// query
 		final SolrQuery solrQuery = new SolrQuery("*:*");
 		if (StringUtils.hasText(query)) {